Diseases of the vascular system afflict a substantial portion of the adult population. Many of these diseases are life-threatening conditions that demand substantial surgical intervention. For example, a stenoses or blockage of a blood vessel may develop requiring surgical intervention to open the blood vessel. Although there are traditional surgical procedures that can be effective in treating these conditions, the surgery itself can be taxing and dangerous for the patient. In particular, for many stenoses the surgical procedure requires that the patient's abdominal or chest cavity be opened to reach and expose the stenoses while it is being repaired. This is a highly invasive and dangerous surgical procedure that requires that the surgeon balance the patient's risk of harm from the disease against the patient's risk of harm from the treatment.
To reduce the mortality and morbidity resulting from these highly invasive surgical procedures, and to provide surgical treatments suitable for treating a broad range of patients, percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA) techniques have been developed to reduce arterial build-up of cholesterol fats or atherosclerotic plaque. In one such procedure, a guide wire is typically maneuvered through an opening in the vascular system to the site of the stenosis. A catheter is then advanced over the guide wire through the vascular system and to the site of the stenosis. A balloon catheter is then advanced through the guide catheter so that the balloon of the balloon catheter may be property positioned within the stenosed region of the blood vessel. To alleviate the deleterious effects of the stenosis, the balloon at the distal end of the catheter is inflated to widen the blood vessel at the site of the stenosis.
Widening a blood vessel in this manner can cause flaps, fissures and dissections to form on the site of the blood vessel, which can thus cause the dilated vessel to reclose. Additionally, restenosis can occur whereby the blood vessel returns of its own accord to its original stenosed condition. To prevent reclosure or restenosis, a metal stent is typically deployed dwing the PTA or PTCA procedure to reinforce the blood vessel wall and to hold the flaps, fissures and dissections in place.
In many operations, it is necessary to deploy more than one stent during a single PTA or PTCA procedure due to the length of the stenosis in the vascular tissue. Additionally, it is often commercially advantageous to provide separately the balloon catheter and the stent so that the surgeon performing the operation can choose the appropriate stent and balloon catheter to repair the occluded blood vessel given the nature of the stenosis and the diameter of the blood vessel. Accordingly, it is frequently necessary to load a stent onto a balloon catheter prior to or during performance of the surgical procedure.
Positioning the stent on the balloon presents a number of difficulties. The balloon typically is formed from a very thin material that may be damaged if the stent is slid over the surface of the balloon during the loading procedure. This is particularly true when the stent is formed using a laser cutting procedure in which edges of the stent may be sufficiently sharp as to scratch or puncture the balloon. A scratch or puncture may increase the risk that the balloon will burst during inflation with potentially life threatening consequences to the patient. Likewise, sliding the stent with respect to the balloon may cause the stent to snag on the balloon thus deforming the stent and rendering it useless for performing PTA or PTCA.
Accordingly, it would be desirable to provide a stent mounting and transfer device for mounting a stent onto a balloon catheter which is inexpensive to manufiacture and which will reliably cause the stent to be delivered onto the balloon without damaging the balloon or deforming the stent. Additionally, it would be desirable to provide a stent mounting and transfer device which is easy and quick to use.